Sprayer pumps needing continuous fluid spraying are known to use miniature gear pumps to lift fluid from a reservoir and to develop the necessary pressure to enable a sprayer head to breakup the fluid sufficiently to generate a non-pulsating spray. Priming such pumps may take 10 seconds or more to replace air in a dip tube or delivery line with fluid. Expensive precision parts may be needed to lift a fluid more than a few inches. A check valve to prevent backflow to the reservoir may be needed to prevent losing the prime at the pump.
Fluids having surfactants therein are difficult to contain without leakage. Dribble at a sprayer head is especially undesirable. A check valve is often used immediately upstream of the sprayer head to minimize fluid volume available for dribble at the sprayer head outlet. The check valve typically has a cracking pressure or threshold pressure that has to be exceeded before fluid flow to the sprayer head may occur. The combination of suction needed for pump priming and fluid lifting, as well as the discharge cracking pressure, may be too much for an inexpensive gear pump to overcome.
What is needed is a simple gear pump and reservoir combination which minimizes the necessary suction for pump priming and fluid lifting so that a cracking pressure as high as 3.5 psig is exceeded by the pump. In addition, what is needed is a self-priming gear pump that is primed in one or two seconds. Furthermore, what is needed is a replaceable fluid reservoir that may be connected to a gear pump simply, yet in a leak-resistant manner.